The present invention relates generally to a data transmission system, and more particularly pertains to a data transmission system for transporting a plurality of parallel digital words.
In a chemical processing plant, there are many functions which must be controlled simultaneously for the chemical plant to operate properly. These control functions include the setting of many valve positions to control the flow rates of chemicals through the plant. A new type of control valve being utilized in these chemical processing plants requires a twelve bit parallel digital word to control the valve function, which would require thirteen separate wires running between each controller and each valve. It may be readily seen that if many of these valves are used at a given location, the running of many sets of thirteen wires could be quite expensive and bulky. The present invention allows a number of controllers to control a similar number of valves with only two twisted pair shielded wires running between the group of controllers and the group of valves.